1. Field of the Invention:
The present invention relates to a joint means having flanges. More particularly, the present invention pertains to an improvement in a joint means in which a closed loopshaped sealing member which is interposed between two flanges is formed by wrapping a thin metal sheet around heat resistant material.
2. Description of the Related Art:
In general, the exhaust gas discharged from various kinds of exhaust gas generating sources, for example, automotive engines, is emitted into the atmosphere through a relatively long exhaust pipe connected at one end thereof to the exhaust manifold of the engine.
It is a general practice to provide a muffler and a catalytic converter at an intermediate portion of such an exhaust pipe in order to damp noise associated with the exhaust gas and to render harmless certain noxious components contained therein.
Associated parts such as the muffler and the catalytic converter are produced separately from the exhaust pipe and are joined to the intermediate portion of the pipe using a joint means. This joint means must be airtight so that no exhaust gas leaks from the exhaust pipe. Accordingly, two pipe end portions which constitute a joint means have respective flanges which extend outwardly. These flanges are fastened to each other by means of bolts with a sealing member interposed between the flanges. Since the temperature of exhaust gas is relatively high, it is a general practice to employ a sealing member having high heat resistance and relatively high rigidity. Since a sealing member having a relatively high rigidity contacts the surface of a flange in a state close to line contact, it is necessary, in order to obtain satisfactory exhaust sealing performance, to precisely machine the flange surface which is to be contacted by the sealing member so that said surface has a high degree of accuracy in terms of surface roughness and flatness. Thus, the conventional method of making a joint means involves a difficult process for machining the flanges. In addition, at least one of the two flanges needs to have a groove formed therein for positioning the sealing member, and it is particularly difficult to finish this groove with a high degree of accuracy.